Standard Model
Written by John Carl Villanueva
The Standard Model is particle physics' most widely accepted model for the basic building blocks of matter as well as their interactions with one another. The consistency of the model has been tested, and found to hold, in high-energy physics laboratories worldwide.
At the heart of the Standard Model are the fundamental particles themselves and the interactions involved. The fundamental particles, i.e., those that (at this point) have no substructure, include quarks, leptons, and gauge bosons. On the other hand, the interactions include the electromagnetic, weak, strong, as well as the gravitational interaction.
To form composite particles like protons and neutrons, force mediating particles are exchanged between fundamental particles. For example, quarks exchange gluons in the strong interaction to form protons or neutrons. The known force mediating particles are the photons, W+, W-, Z, and gluons. Gravitons, which are believed to mediate for the gravitational interactions, have not yet been observed.
Among the fundamental particles, the quarks are the most active, participating in strong, weak, electromagnetic and gravitational interactions by mediating gluons, photons, W and Z bosons, and gravitons (if they do exist) respectively.
The fundamental particles have different types or flavors. Among the particles considered as flavors of leptons are neutrinos, electrons, muons, and taus. You might be glad to know that the quark flavors have more simple sounding names: up, down, charm, strange, top, and bottom.
It's not difficult to imagine that, with all the tiny particles popping up, scientists may have grown tired of coming up with sophisticated names. Then again, that's also probably one way of preventing people from becoming intimidated with physics.
The Standard Model can trace its direct roots to Sheldon Glashow's discovery of a way to combine the electromagnetic and weak interactions. Four years later, in 1967, Steven Weinberg and Abdus Salam introduced the Higgs mechanism. Further contributions to the field earned these three scientists a shared Nobel Prize in Physics.
Today, the Standard Model reigns supreme in explaining the structure of the tiniest of the tiny. Note, however, that such models are continuously evolving. Let us not forget that the atoms were once considered fundamental. Then came the electrons, protons, and neutrons. Now, we have quarks, leptons, and bosons.
It should therefore not surprise us that, with the invention of stronger particle accelerators and colliders, we will later on discover even more fundamental particles. The Large Hadron Collider (LHC) at CERN, which, once operational in October 2009, will be the world's largest and most powerful particle accelerator. Who knows what pieces will be discovered after smashing atoms (or even quarks perhaps?) into smithereens?
You can read more about the Standard Model and fundamental particles here in Universe Today. Want to know how Fermilab is putting the squeeze on the Higgs Boson? How about the possibility of the LHC to detect 'unparticles'?
There's more about it at Physics World. Here are a couple of sources there:
Here are two episodes at Astronomy Cast that you might want to check out as well:
- Dangerous Solar Flares, Higgs Boson Insights, and Light Speed Flashlights
- Nucleosynthesis: Elements from Stars
Filed under: Astronomy
Tags: bosons, CERN, fundamental particles, gluons, leptons, LHC, quarks, standard model, strong interaction, weak interaction
